ZLV Online

The aim of the article is the investigation of potential importance of air humidity in ash dieback epidemiology. The investigation linked up to the previous investigation of the disease impact in different types of ash vegetation in the Lusatian Mountains Protected Landscape Area, Czech Republic. The sensors Datalogger Minikin THi (EMS Brno) measuring the air humidity were installed in 50 permanent plots respecting the diversity of ash stands in the area. The air humidity was measured 4.5 m above ground level in the centre of research plots. The data were recorded in 15-min intervals during June and August 2012 (the main period of ascosporic spread). The data were compared to extent of damage caused by ash dieback in research plots. It was found out that the average air humidity statistically differed among vegetation types and corresponded to the disease impact. The highest level of air humidity was in riparian stands and in ash-alder mixed alluvial forest – i.e. in vegetation types with the highest disease impact. The lowest air humidity was recorded in isolated trees in open landscape, which were the less affected category of ash vegetation. Moreover, the statistically evident regression of extent of ash damage on the air humidity was found out.